Integrated system for controlling plural surgical tools

ABSTRACT

A surgical tool system including plural powered surgical handpieces. The handpieces are removably connected to a single control console. The control console has a power supply. A controller internal to the control console simultaneously supplies power to the plural handpieces. In the event the handpieces collectively draw more power than the power supply can provide, the control console temporarily stops the application of power to one of the handpieces.

RELATIONSHIP TO EARLIER FILED APPLICATION

This application claims priority under 35 U.S.C. Sec 119 fromProvisional Application No. ______, having the same title as thisapplication filed Sep. 29, 2004 under Express Mail Label No. ER 575709335 US.

FIELD OF THE INVENTION

This invention is related generally to a system for powering surgicaltools. More particularly, this invention is related to a system forsimultaneously powering surgical tools that have different powerrequirements.

BACKGROUND OF THE INVENTION

In modern surgery, powered surgical tools are some of the most importantinstruments medical personnel have available to them for performingcertain surgical procedures. Many surgical tools take the form of sometype of motorized handpiece to which a cutting accessory like a drillbit, a bur or a saw blade are attached. These tools are used toselectively remove small sections of hard or soft tissue or to separatesections of tissue. The ability to use powered surgical tools on apatient has lessened the physical strain of physicians and otherpersonnel when performing surgical procedures on a patient. Moreover,most surgical procedures can be performed more quickly and moreaccurately with powered surgical tools than with the manual equivalentsthat preceded them.

A typical powered surgical tool system, in addition to the handpiece,includes a control console and a cable that connects the handpiece tothe console. The control console contains the electronic circuitry thatconverts the available line voltage into energization voltage suitablefor powering the motor integral with the handpiece. Typically, thecontrol console is connected to receive a signal from the hand or footswitch used to control the tool; based on that signal, the console sendsappropriate energization signals to the handpiece so as to cause it tooperate at the desired speed.

As the use of powered surgical tools has expanded, so has thedevelopment of different kinds of powered surgical tools that performdifferent surgical tasks. For example, a femoral reamer, used in hipreplacement surgery is a relatively slow speed drill that operates atapproximately 100 RPM, yet it draws a relatively high amount of power,approximately 400 Watts. Neurosurgery requires the use of a craniotomewhich is a very high powered drill that operates at approximately 75,000RPM and that requires a medium amount of power, approximately 150 Watts.In ear, nose and throat surgery, micro drills are often employed. Atypical micro drill rotates between approximately 10,000 and 40,000 RPMand requires only a relatively small amount of power, approximately 40Watts.

As the number of different types of powered surgical tools haveexpanded, it has become necessary to provide each type of handpiece amechanism for ensuring that it receives the appropriate energizationsignals. The conventional solution to this problem has been to provideeach handpiece with its own power console. As can readily be understood,this solution is expensive in that it requires hospitals and othersurgical facilities to keep a number of different consoles available, inthe event a specific set of tools are required to perform a givensurgical procedure. Moreover, in the event a number of differentsurgical tools are required in order to perform a given surgicalprocedure, it is necessary to provide the operating suite with theindividual consoles required by the different handpieces. Having toprovide these different consoles contributes to clutter in the operatingsuite.

An attempt to resolve this issue has been to design consoles that supplypower to different handpieces. While these consoles have performedsatisfactorily, they are not without their own disadvantages. Many ofthese consoles are arranged so that the medical personnel have tomanually preset their internal electronics in order to ensure that theybe provided the desired energization signals to the tools to which theyare connected. Moreover, given the inevitable human error factor, timealso needs to be spent to ensure that once configured for a new tool, aconsole is, in fact, properly configured. Requiring medical personnel toperform these tasks takes away from the time the personnel could beattending to the needs of the patient.

The Applicant's Assignee's U.S. Pat. No. 6,017,354, INTEGRATED SYSTEMFOR POWERED SURGICAL TOOLS, issued Jan. 25, 2000 the contents of whichis explicitly incorporated herein by reference, appreciably eliminatesthe need to bring different control consoles into an operating room whensurgical handpieces having different power requirements are used. In thedisclosed system, each handpiece contains a NOVRAM. The NOVRAM storesdata identifying the electrical power needs of the energy-producingcomponent in the handpiece. The system also includes control consoleincludes a processor and an energization circuit that for supplyingenergization signals applied to the handpiece. The types of theenergization signals the energization circuit supplies to the handpiecevary as a function of command signals sent by the processor. Upon theconnection of a handpiece to the control console, the data in thehandpiece NOVRAM are read. These data are then used by the processor toregulate the output of energization signals by the energization circuitso that the appropriate energization signals are supplied to thehandpiece.

Still another feature of the prior art system is that it is possible tosimultaneously connect plural handpieces to the control console. Theprocessor simultaneously stores the energization signal-describing datafor each connected handpiece.

Thus, the prior art system, for many surgical procedures, essentiallyeliminated the need to provide an operating room with plural controlconsoles just because the handpieces being used had different powerrequirements. Moreover, the above system was further designed so thatthe console could be used to sequentially energize different handpieceswithout first having to remove the first and handpiece and then installthe second handpiece.

Clearly, the prior art system provided a number of different cost andtime efficiencies to the operating room. However, this system can, at agiven instant, only supply power to a single handpiece. There areinstances wherein for efficiency or necessity it is desirable tosimultaneously actuate plural handpieces during a surgical procedure.For example, sometimes one surgeon will be harvesting tissue from oneportion of a patient while a second surgeon is preparing another portionof the patient's body for insertion of the tissue. The present system isnot able to simultaneously power the two separate surgical handpiecesused to perform these separate procedures. If, in the interest ofefficiency, there is an interest in performing these proceduressimultaneously, two separate control consoles must be provided.

Moreover, many surgeons use footswitches to control their surgicalhandpieces and accessory instruments, for example, irrigation andsuction pumps. It is a common practice to provide, on a singlefootswitch assembly, a number of different footswitches for controllinga number of different functions. For example, a single footswitchassembly may have individual footswitches for controlling the on/offstate of the handpiece motor, the speed of the handpiece motor, theforward/reverse/oscillate direction of the handpiece motor and whetheror not irrigation fluid is to be supplied.

Another limitation associated with known systems for driving motorizedsurgical handpieces concerns their ability to control the associatedhandpieces when the motors are operating at low RPMs. This problem isespecially prevalent in systems employed to drive handpieces thatinclude brushless, sensorless DC motors. The known systems operate bymonitoring the back electromotive force voltage (BEMF signal) producedat the unenergized winding of the motor. A limitation associated withthis control technique is that, when the motor is operating at a lowRPM, the BEMF signal is often so low that it is difficult, if notimpossible, to measure. Once this signal is undetectable, it can be nolonger user to regular the commutation of the windings. Instead, brutforce means are often used when the motor is started up in order toinitially actuate the rotor. Also, this typical means that once a motorstalls as result of the motor reaching limit as the amount of torquethat it can develop, the surgeon must totally deactivate, turn off, themotor before, the complementary control console can again apply acommutation signal to the windings. This results in the undesirableslowing of the surgical procedure.

SUMMARY OF THE INVENTION

This invention is related to a new and useful surgical tool system. Thesurgical tool system of this invention includes a control console.Internal to the control console is a motor controller capable ofsimultaneously energizing plural surgical handpieces. The controlconsole also includes a display controller. The display controllerfunctions as the main controller for the system. The display controllerserves as the controller for the console. The display controller iscapability of reading the data in the NOVRAMs in the handpiecesconnected to the console. Based on these data, additional data read bythe console, externally generated commands and surgeon-entered commands,the main processor directs the motor controller to energize thehandpieces.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the claims. The aboveand further features of the invention may be better understood byreference to the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 depicts the basic components of the system of this invention;

FIGS. 2A and 2B collectively form a block diagram of the majorcomponents internal to the control console of the system of thisinvention;

FIG. 3 is a block diagram of the sub-circuits internal to the powersupply of the control console;

FIG. 4 is a block diagram of the display controller and the componentsperipheral to the display controller;

FIG. 5 depicts the records contained within an exemplary procedurepreference file;

FIG. 6 depicts the records contained within an exemplary master usersdirectory;

FIG. 7 depicts the records contained within an exemplary preferencedirectory;

FIG. 8 is an example of the records contained within the activepreference table;

FIG. 9 depicts the image presented on the display to invite theselection of an active preference;

FIG. 10 is a table illustrating the data fields within footswitchassignment table;

FIG. 11 is a flow chart of the basic process steps used by the controlconsole to assign the footswitches control of the handpieces coupled tothe control console;

FIG. 12 is a diagram depicting a basic footswitch mapping image that ispresented on the control console display;

FIG. 13 is a diagram depicting components of the run time imagepresented on the control console display;

FIG. 14 is a flow chart of the process steps performed by the controlconsole when a handpiece is placed in the dual control mode;

FIGS. 15A and 15B, when assembled together, form a block diagram of themain components of the motor controller;

FIGS. 16A, 16B and 16C, when assembled together form a block and partialschematic diagram of the H bridge of the motor controller;

FIG. 17 is schematic representation of the stator windings of ahandpiece motor;

FIG. 18 is a block and partial schematic diagram of the circuit used tomonitor the power supply voltage;

FIG. 19 is a block and partial schematic diagram of the circuit used tomonitor the BEMF signals produced across the windings of the handpiecemotor;

FIG. 20 is a block diagram of the circuit used to monitor the currentdrawn by the handpiece motor;

FIG. 21 is a block diagram of the circuit used to convert a number ofthe monitored signals into digital signals;

FIG. 22 is a block diagram of the circuit used to convert the monitoredcurrent signal into a digital signal;

FIG. 23 is a block and partially schematic of one of the relayassemblies that for the motor multiplexer of the motor controller;

FIG. 24 depicts the records contained in the power driver assignmenttable;

FIG. 25 is a graph of current over time depicting the measured currentof a handpiece motor when the system is an inductance sensing mode forthe motor;

FIG. 26 is a graph of the relationship of measured current to motorrotor position for a surgical handpiece;

FIG. 27 depicts how a handpiece NOVRAM of the system of this inventionincludes gain and offset data to facilitate the inductive signal sensingof the handpiece rotor;

FIG. 28 is a graph of calibrated measured rotor current to motor rotorposition when inductive sensing is performed;

FIG. 29 is flow chart of the process steps executed by the motorcontroller during inductance sensing mode to determine whether or not,based on a transition to particular motor pole state, the motor rotorshould be have considered to have shifted position;

FIG. 30 is a flow chart of the process steps executed by the motorcontroller to during the inductance sensing mode to determine whether ornot the gain and offset calibration values for a particular motor phaseshould be recalibrated;

FIG. 31 is a flow chart of the process steps employed during handpiecemanufacture and during operation of the system to user inter-commutationposition calculations to, in inductance sensing mode, determine motorrotor position;

FIGS. 32A and 32B collectively represent the processes executed by themotor processor and a single field programmable gate array of the motorcontrol to regulate the energization of a handpiece;

FIG. 33 is a block and partial schematic drawing of the circuit thatselectively asserts the power supply limit signal;

FIG. 34A is a graphic depiction of the BEMF signal over time and FIG.34B depicts how, according the BEMF signal is measured according to thisinvention to determine motor rotor position; and

FIGS. 35A and 35B, when assembled together form a block and partialschematic diagram of the handpiece interface.

DETAILED DESCRIPTION

FIGS. 1, 2A and 2B illustrate the basic features of a surgical toolsystem 30 of this invention. System 30 includes a control console 32.The control console 32 is used to actuate one or more handpieces 34. InFIG. 1, a single handpiece 34, a saw, is illustrated. As seen byreference to FIG. 2B, it is possible to simultaneously connect threehandpieces 34, to the control console 32. In the depicted version of theinvention, internal to the handpiece 34 is a motor 36 (depicted as aphantom box) and a gear assembly (gear assembly not illustrated). Eachhandpiece 34 drives a cutting accessory 35 that is typically removablyattached to the handpiece. In the illustrated handpiece 34 of FIG. 1,cutting accessory 35 is a saw blade that is removably attached to thedistal end of the handpiece. (“Distal” means away from thesurgeon/towards the patient. “Proximal” means towards the surgeon/awayfrom the patient.) The illustrated handpiece 34 has a gear assemblydesigned to oscillate the saw blade back and forth. Other motorizedhandpieces 34 may be provided with other motor and gear assemblies todrive the associated cutting accessories in rotational movement. It isalso recognized that a handpiece 34 typically has coupling assembly,represented by identification number 33 in FIG. 1, that releasably holdsthe cutting accessory 35 to the handpiece.

Each handpiece 34 is removably attached to a control console 32 by aflexible cable 38. The control console has multiple sockets 40. Eachsocket 40 is capable of receiving a separate cable 38. This allows themultiple handpieces 34 to simultaneously be connected to the controlconsole 32.

Control console 32 has a display 42 with a touch screen surface.Commands for regulating the components of the system 30 are entered intothe control console by depressing buttons presented as images on display42. Commands are also entered into control console 16 by other controlswitches. These switches may be integral with the handpieces 34.Alternatively, these switches may be individual switches that are partof a footswitch assembly 44 also attached to the control console 32. InFIG. 1, a single footswitch assembly 44 is shown connected to thecontrol console 32 by a cable 46. Control console 32 is provided withtwo sockets 48 for receiving two cables 46. This allows two footswitchassemblies 44 a and 44 b as seen in FIG. 2B to be simultaneouslyattached to the control console 16.

A pump 50 is also attached to the control console 32. Pump 50 includes atube set 52 that is removably attached to the control console 32. Tubeset 52 includes tubing 54 that provides a fluid path from a bag ofirrigation fluid 56 to an irrigation clip 58 attached to the handpiece34. Pump 50 also includes a motor 60 (FIG. 2B) disposed inside thecontrol console 324.

FIG. 2A and 2B, when assembled together, illustrate the main componentsinternal to control console 30. These components include a displaycontroller 64. Display controller 64 controls the output of imagespresented on display 42, represented as LCD (liquid crystal display) inFIG. 2A. The display controller 64 also serves as the overall controllerfor the control console 32. Thus, the display controller 64 receives thevarious input signals generated to control the operation of theequipment attached to the console 32, and causes the other componentsinternal to the console to generate the appropriate output signals.

Thus, display controller 64 is connected to a touch screen signalprocessor 66. The touch screen signal processor 66 monitors thedepression of the touch screen layer over the display 28. Touch screenprocessor 66 upon detecting the depression of a portion of the touchscreen layer, informs the display controller 64 of which section of thescreen was depressed. Display controller 64 uses this information todetermine which of the buttons presented on the display 42 wasdepressed.

Display controller 64 is also connected to a network interface 68,represented as the 1394 Interface in FIG. 2A. Network interface 68serves as the device over which, by a network (not illustrated), thedisplay controller 68 exchanges information about system 30 with otherequipment used to facilitate the performance of the surgical procedure.One such piece of equipment may be a surgical navigation unit. When thecontrol console 32 is connected to this type of component, displaycontroller 64 will inform the surgical navigation unit about the typesof handpieces 34, 34, 34 that are connected to the control console andthe specific types of cutting accessories attached to the individualhandpieces. The surgical navigation unit uses the data to generateinformation displaying where, on or in the patient's body, thehandpieces and cutting accessories are located.

Alternatively, the control console 30 may be connected to a voicerecognition surgical control head. This type of device receives thesurgeon's voice commands directing the operation of the surgicalequipments. Examples of such commands are “Shaver, faster” and“Irrigation, on”. In response to receipt of a specific spoken command,the voice recognition control head converts the command into a specificinstruction packet. This packet is forwarded to the display controller64 through the network interface 68.

Display controller 64 and network interface 68 are exchange signals overa dedicated SPI bus 69.

Control console 32 also includes three handpiece interfaces 70. Eachhandpiece interface 70, is through a separate one of the sockets 40 anda cable 38 is connected to a separate one of the handpieces 34. Eachhandpiece interface 70 exchanges signals with components internal to theassociated handpiece 34.

Components internal to a handpiece 34 that exchange signals with thehandpiece interface 70 are sensors. For example, one handpiece may havea first sensor that monitors the temperature of the motor 36 internal tothe handpiece. The same handpiece 34 may have a second sensor thatgenerates an analog signal as function of the displacement of a switchlever on the handpiece. The output signal from this sensor thusrepresents the surgeon-selected speed for the handpiece motor 36.Another handpiece may have a sensor that generates a signal is afunction of the open/closed state of valve that regulates irrigationflow through the handpiece. Based on the state of this valve, thedisplay controller 64 may increase the speed of the pump motor 60 toincrease/decrease the rate at which irrigation fluid is supplied to thehandpiece 34.

Handpiece interface 70 is also capable of forwarding signals tocomponents internal to the handpiece 34. For example, a handpiece mayinclude a component that emits light, RF waves or an acoustic signal.The signal emitted by this device is used by the surgical navigationsystem to track the location of the handpiece. The energization signalfor that actuates this component is transmitted to from the controlconsole 32 through the handpiece interface 70.

Control console 32 also includes two footswitch interfaces 74. Eachfootswitch interface 74, through a separate one of the sockets 48 and acable 46, exchanges signals with a separate one of the footswitchassemblies 44. More particularly, each footswitch 44 includes one ormore pressure sensitive sensors that generate signals in response todepression of a specific pad on the footswitch assembly. Each footswitchinterface 74 reads the data from the footswitch sensors of thefootswitch to which the interface is connected.

The handpiece interfaces 70 and footswitch interfaces 74 are connectedto the display controller by a common first UART bus 76.

Control console 32 also includes a NOVRAM interface 78. The NOVRAMinterface reads the data in memories internal to the handpieces 34 andfootswitch assemblies 44. Specifically, internal to each handpiece 34that exchanges signals with the handpiece interface is a NOVRAM 72. EachNOVRAM 72 contains data specific to the operation of the handpiece 34which the NOVRAM is mounted. Examples of such data include the minimumand maximum speeds at which the motor internal to the handpiece shoulddevelop, and the maximum torque the motor should produce at a givenspeed. The handpiece NOVRAMs 72 also contain data that identifies thetype of sensors in the handpiece 34 and data that facilitates theprocessing of the output signals from the sensors. The above-referencedU.S. Pat. No. 6,017,354, which is incorporated herein by reference,offers a more detailed list of types of data stored in the NOVRAM 72.

While not illustrated, it should be understood that each handpiece alsocontains an EEPROM. NOVRAM interface 78 is capable of reading data fromand writing data to the handpiece EEPROMs. The data written to thehandpiece EEPROMs include data indicating elapsed time the handpiece 34has been actuated and data identifying any faults detected during theoperation of the handpiece.

Each footswitch assembly 44 also contains a NOVRAM (footswitch assemblyNOVRAMs not illustrated). Each footswitch NOVRAM contains datadescribing the configuration of the associated footswitch assembly 44and data useful for processing the signals generated by the sensorsinternal to the assembly.

A pump controller 80 is also incorporated into the control console 34.Pump controller 80, in response to commands from the display controller64, regulates the on/off actuation of the pump motor 60. The pumpcontroller 80 also regulates the speed at which the pump motor 60 isactuated so as to regulate the rate at which irrigation fluid isdischarged from pump 50. In one version of the invention, the primarycomponent about which the circuit forming the pump controller 80 isconstructed is the ATmega8 microcontroller available from AtmelCorporation of San Jose, Calif., USA.

Control console 32 also has an RFID interface 82. The RFID interface 32exchanges signals with any radio frequency identification devices(RFIDs) that are connected to the control console 32 (RFIDs notillustrated). Each RFID contains a memory and a circuit that facilitatesthe reading of data from and writing of data to the memory. Each cuttingaccessory 35 attached to an individual handpiece 34 may have an RFID.Each RFID integral with a cutting accessory 35 contains data describingthe characteristics of the cutting accessory. These data may describethe physical characteristics of the cutting accessory and/or the speedand direction at which the cutting accessory should be driven. TheApplicant's U.S. patent application Ser. No. 10/214,937, SURGICAL TOOLSYSTEM WITH COMPONENTS THAT PERFORM INDUCTIVE SIGNAL TRANSFER, filedAug. 8, 2002, U.S. Patent Publication No. US 2003/0093103 A1, now U.S.Pat. No. ______, which is explicitly incorporated herein by reference,provides a detailed instruction of how data in a cutting accessory RFIDis used to regulate the actuation of the handpiece 34 to which thecutting accessory 35 is attached.

An RFID may also be attached to either the tube set 52 of the pump 50 orthe bag 56 holding the pumped irrigation fluid. The data in the tube setRFID describes the characteristics of the tube set 52. The data in thebag RFID describes the characteristics of the contents of the bag 56.The Applicant's U.S. patent application No. ______, SURGICAL TOOL SYSTEMWITH INTEGRATED PUMP, filed Sep. 28, 2004 under Express Mail Label No.US 57 57 03 284, U.S. Patent Publication No. ______, now U.S. Pat. No.______, which is explicitly incorporated herein by reference, provides adetailed explanation of how the data in the RFIDs within a tube set 52and a fluid bag 56 are used to regulate the actuation of the pump 50.

The RFID interface 82 reads the data from and writes data to the cuttingaccessory, tube set and fluid bag RFIDs. Signals are transferred betweenthe RFID interface 82 and the individual RFIDs by inductive signalstransfer. Not shown are the coils in the control console 32 thatfacilitate signal transfer between the tube set 52 and fluid bag 56RFIDs. Similarly not shown are the coils internal to the handpieces 34that facilitate the signal exchange between the control console 32 andthe cutting accessories 35 attached to the handpieces. RFID interface 82is constructed out of one or more SL RC400 I-CODE Readers available fromPhilips Semiconductors of Eindhoven, The Netherlands.

The NOVRAM interface 78, the pump controller 80 and the RFID interface82, forward data to and receive instructions from the display controller64 over a second UART bus 84

Control console 32 also includes a motor controller 86. Motor controller86 is the circuit that, based on instructions from the displaycontroller 64, generates the energization signals to the motors 36 otherpower-consuming units internal to the handpiece 34. Motor controller 86is simultaneously connected to the three handpieces through the sockets40 and cables 38. The motor controller 86 provides data and receivesinstructions from the display controller 64 over a second SPI bus 88.

As seen by reference to FIG. 3, also internal to the control console isa power supply 90. Power supply 90 includes an AC to DC converter 82.The AC/DC converter 92 converts the line signal into a 40 VDC signal.This 40 VDC is the signal applied to the handpiece 34 by motorcontroller 86. The signal flow of the line voltage into the AC/DCconverter is controlled by a single pull double throw switch 94. Switch94 thus functions as the main on/off switch for the control console 94.Internal to the AC/DC converter are a series of chokes that filter theline signal and a bridge rectifier that converts and filters the linesignal into a DC voltage. A UCC38500 power manager available from TexasInstruments of Dallas, Tex., is used to perform power factor correctionof the output signal. A boosted DC signal, at 380V, is then pulse wavemodulated across a step down transfer. The output signal from thetransformer is rectified and filtered to produce the 40 VDC outputsignal. In order to reduce the complexity of the drawings, unlessnecessary, the buses along which the 40 VDC signal and the other outputsignals produced by power supply 40 are not shown.

In addition to being applied to the handpieces 34, the 40 VDC is alsoapplied to a digital power supply 96 also part of the power supply 90.The power supply 96, components not illustrated, converts the 40 VDCsignal into a 12 VDC, 7 VDC, 5 VDC, 3.3 VDC, 2.5 VDC 1.8 VDC 1.26 VDCand −5 VDC signals. All of the above signals but the 7 VDC signal aremade available on buses for use by other components internal to thecontrol console 32.

The 12 VDC, seven VDC and −DVD signals produced power supply 96 areforwarded to an analog power supply 98, also part of power supply 90.Based on the input signals, power supply 98 produces 8 V, 5 V and −3.5 Vprecision, constant analog signals. The analog signals produced byconverter 98 are used by sensing circuits internal to the controlconsole 32. Power supply 98 also produced a VREF signal. Typically theVREF signal is 2.5 Volts.

Display controller 64 and the components peripheral to it are nowdescribed by reference to FIG. 4. The display controller 64 is anysuitable microprocessor. One potential microprocessor is theGDPXA255A0C300 processor from the Intel Corporation of Santa Clara,Calif. Both SDRAM 102 and a flash memory 104 are connected to thedisplay controller 64. The SDRAM 102 holds operating instructions anddata for run time use by the display controller 64. Flash memory 104 isa non-volatile memory that stores the perimante operating instructionsfor the display controller 64 and calibration data for touch screen 66.The SDRAM 102 and flash memory 104 are connected to the displaycontroller 64 by a common bus 106.

A collection of sub-circuits, broadly referred to as interface 108, arealso connected to display controller 64. Internal to interface 108 arethe individual sub-circuits that control the exchange of signals betweenthe display controller 64 and the buses internal to the other componentswithin control console 32. These sub-circuits include the circuits thatfacilitate the exchange of signals over the two SPI buses 69 and 88, theUART buses 76 and 84 and with the display 42 and touch screen signalprocessor 66. Interface 108 also includes a circuit for facilitatingsignal exchange over a USB bus 110 internal to the control console 32.

Signals are exchanged between display controller 64 and the sub-circuitsforming interface 108 over a collection of conductors generallyidentified as bus 112. It should be recognized that the exchange ofsignals between the display controller and the individual sub-circuitsforming interface 108 is, between the sub-circuits, asynchronous.

A number of additional peripheral devices, while not illustrated shouldfurther be understood to be connected to display controller 64. Theseparts include a crystal that provides a clock signal to the displaycontroller 64. There are circuits that provide a stable power supply andshort life back-up power supply to the display controller 64 and thesub-circuits forming interface 108.

When system 10 of this invention is initially set up to run, displaycontroller 64 reads the data in the handpiece NOVRAMs 72, the footswitchassembly NOVRAMs, and the RFIDs' internal to the cutting accessories 35and the pump tube set 52. Based on these data as well as any additionaldata entered by the operating room personal, the system is configuredfor operation. For example, absent any additional instructions, based onthe data received from a handpiece NOVRAM 72 and the RFID of thecomplementary cutting accessory 35 attached to the handpiece, displayconsole 64 establishes for the handpiece the speed range in which itsmotor 36 should operate and preferred or default speed. This latterspeed is the initial operating speed of the motor if it is operated atsingle speed. Display controller will also cause to be presented ondisplay 42 an image that identifies the handpiece and cutting accessorycombination.

Based on data read from the footswitch assembly NOVRAM, displaycontroller 64 determines what correction factors need to be provided tothe analog input signals generated by the sensors internal to theassembly. Based on data from the RFID internal to the pump tube set 52,the display controller 64 establishes the speed at which the pump motor62 should run in order to discharge irrigation fluid at a specified flowrate.

Once the system 10 is configured for operation, surgeons actuate thevarious components, i.e., the handpieces 34 and pump 50 by enteringcommands into the control console 32. These commands may be entered bydepressing pedals on the footswitch assemblies 44 or by depressingcontrol buttons on the handpieces 34 or that are presented on display42. Spoken commands may also be entered with a voice recognitionsurgical control head through network interface 68. Based on thesecommands, display controller 64 sends specific commands to thecomponents internal to the control console. Primarily these commands aresent to motor controller 86 to actuate one or more of the handpieces 34.Some commands are sent to the pump controller 80 to actuate the pumpmotor 60.

Internal to flash memory 104 associated with the display controller 64are a number of procedure preference files 116, one of which is nowdescribed by reference to FIG. 5. Each procedure preference file 116indicates how, as an alternative to the default settings, one or morecomponents of the system 10 are to be configured for operation during aspecific surgical procedure. Each procedure preference file 116 containsone or more component preference fields 118. Each preference fieldcontains two sub-fields, (not identified). The first sub field includesdata identifying the component to be configured, the second sub fieldidentifies how the component is to be configured.

In the illustrated preference file 116, the first component preferencefield 118 contains data indicating that the preferred setting, theinitial setting for the speed of a universal drill handpiece is to beset at rate different than the default setting in the handpiece NOVRAM72. The second component preference field 118 contains data indicatingthe maximum speed for the universal drill handpiece is to be set at arate different than the rated maximum speed specified by NOVRAM 72.(This alternative maximum speed is less than the rated maximum speed.)The third component preference field 118 contains data indicatingwhether or not the pump 50 is to be actuated when the handpiece 34 isactuated. Data regarding the preferred flow rate at which the pump 50 isto be actuated are stored in the fourth component preference field 118.The fifth component preference field 118 contains data regarding whichindividual footswitch pedals should be mapped to control the operationof the handpiece 34 and pump 50.

Preference files 116 may be established for specific procedures, forspecific surgeons and for specific procedures performed by specificsurgeons. Specifically, as seen by reference to FIG. 6, displaycontroller 64 stores in memory a master user directory 122. Userdirectory 122 includes a number of user fields 124 each of whichcontains data that identifies a specific individual surgeon orprocedure. The first two and fifth user fields 124 of FIG. 6 identifyspecific surgeons. The third and fourth user fields 124 identifyspecific procedures.

Each user field 124 links to a specific preference directory 126,described with reference to FIG. 7. The depicted preference directory126 is for a specific doctor. Internal to the preference directory 126are preference fields 128 that identify the procedures for which thisdoctor has certain instrument preferences. Each preference field thuscontains data identifying a procedure for which the doctor hasestablished a preference and data identifying the specific preferencefile 116 for that procedure. The preference directory 126 for aprocedure, identifies the system settings individual surgeons have forthe procedure. Each preference field 128 within the directory thusidentifies both the doctor and contains a pointer to that doctor'sspecific preference file 116 for the procedure.

Display controller 64 of this invention also maintains an activepreference table 130, described by reference to FIG. 8. Activepreference table 130 contains records of four system setting preferencesit is system setting preference is stored in a separate activepreference file 132. Each active preference file 132 identifies thespecific active preference and contains a pointer to the specificpreference file 116. The selective active setting preferences can be seton as needed basis.

When the system is set to run, operating personnel can relatively easilyaccess an active preferences image 136 on display 42 now described byreference to FIG. 9. The active preferences image 136 includes four bars138 on which the active preferences stored in table 130 are listed. Alsopresented is a default bar 140. The operating room personnel can thenpress one of the bars 138 or 140 to select a particular preference.Confirmation of the acceptance is performed by depressing the accept(ACCPT) button 142. Once the selected setting preference is confirmed,display controller 64 configures the system according to the data in thefile 116 for the selected preference.

Alternatively, selection and confirmation of the default setting resultsin the display controller 64 configuring the system based on the defaultsettings for the handpieces 34 and cutting accessories 35.

Replacement of one of the active preferences is initiated by selectingthe preference and depressing the NEW PRIMARY button 144.

An advantage of the above feature of the system 10 of this invention isthat it eliminates the need, for commonly used system configurations, tohave to go through a longer multi-step selection process to retrieve thedata in a specific preference file 118.

System 30 of this invention is further configured so that eitherfootswitch assembly 44 can be used to control any one of the handpieces34 connected to the control console 32. In order for system 30 toperform this function, it should be understood that the displaycontroller 64 maintains a table 150, illustrated by FIG. 10, for eachfootswitch assembly 44. The individual fields 152 in table identify thecontrol function assigned to a separate one of the pedals integral withthe footswitch assembly. In the depicted version of the invention,footswitch assembly has five pedals. Therefore, table 150 for thefootswitch assembly has five pedal assignment fields 152. Displaycontroller 64 writes data identifying the function assigned to eachfootswitch pedal into its complementary assignment field 152 based oneither entered established default settings, manually entered preferencecommands or data regarding an individual surgeon's preference that areretrieved from storage.

When a signal is received from one of the footswitch sensors indicatingthe complementary pedal has been actuated, display controller 64, basedon reference to the data in table 150 for the footswitch, generates theappropriate command to cause the appropriate state change of the othercomponent connected to the system.

Display controller 64 also updates the data in the footswitch functiontables to facilitate the switching of control of the handpieces tobetween the footswitches as discussed below.

Specifically, the display controller 64 monitors whether or not ahandpiece cable 38 is connected to each socket 40 and whether or not afootswitch cable 46 is connected to each socket 48. It is assumed thatif a cable 38 is connected to a socket 40, a handpiece 34 is connectedto the distal end of the cable 38. Each footswitch assembly 44 isintegrally attached to a cable 46. Therefore, the connection of a cable38 to the control console automatically results in the connection of afootswitch to the console.

As represented by step 156 in the flow chart of FIG. 11, the initialmonitoring of the handpiece 34 and footswitch 44 connections to thecontrol console 32 is referred to as monitoring whether or not thesystem 30 is in the plug and play mode. System 30 is considered in theplug and play mode if, at a given time less than two handpieces 34 orless than two footswitch assemblies 44 are connected to the controlconsole 32.

If the system is in the plug and play mode, display controller 64, instep 158, assigns that handpieces to the footswitches according to adefault scheme. Specifically under this scheme, if there is just asingle footswitch assembly 44 attached to the control console 32, thecontrol of each attached handpiece 34 is assigned, or mapped, to thatfootswitch. Thus, for each attached handpiece 34, display controller 64writes to the pedal assignment table 150 for the footswitch assembly 44data in one of the function fields 152. These data indicate that thefootswitch pedal associated with the function field 152 controls thespecific handpiece.

Similarly, the system 30 is considered in the plug and play mode whenthere are plural footswitch assemblies 44 and a single handpiece 34attached to the control console 32. Display controller 64 performsdefault mapping for this version of the plug and play mode by mappingcontrol for the handpiece to each footswitch assembly. Thus the displaycontroller 64 writes into the pedal assignment tables 150 for bothhandpieces data indicating that each footswitch can control thehandpiece 34. When both footswitches can control a handpiece, thehandpiece is considered to be the below discussed dual-control state.

If, as a result of the cable connection monitoring of step 156, displaycontroller 64 determines that two or more handpieces 34 and bothfootswitch assemblies 44 are connected to the control console 32, thesystem is considered to be in the multiples mode. Initially, when thesystem 30 enters the multiple mode, display controller 64 maps thefootswitch assignments to what they were in the immediate past plug andplay mode, step 162. Thus, if a single footswitch assembly 44 wascontrolling the plural handpieces, that footswitch assembly initiallyretains control of those handpieces. If both footswitch assemblies had asingle handpiece under dual control, both footswitch assemblies maintainthis control.

After the mapping of step 160 is complete, display controller 64, instep 161, causes a footswitch assignment map 162 to be presented on thedisplay 42, as illustrated by FIG. 12. On map 162, each footswitchassembly is represented by a different color button on the left side ofthe image. In the displayed map a green button 164 is used to representa first footswitch assembly; a yellow button 166 represents the secondfootswitch assembly. Legends 168 a, 168 b and 168 c identify eachhandpiece connected to the control console 34. The data identifying eachhandpiece so this information can be presented in map 162 is from thehandpiece NOVRAMs 72.

Also present on the image of map 162 are color-specific buttons 170 a,170b and 170 c that identify to which footswitch assembly 44 eachhandpiece is presently assigned. Each button 170 a, 170 b and 170 c isimmediately to the right of the legend image 168 a, 168 b and 168 c,respectively, of the handpiece with which the button is associated. Thecolor of each button 170 a, 170 b and 170 c corresponds to the colorassociated with the footswitch assembly 44 presently mapped to controlthe button's handpiece. Map image 162 of FIG. 12 indicates that the 4 mmdrill is under the control of the yellow footswitch assembly, thefootswitch assembly connected to the bottom of the two sockets 48.

As represented by button 170 c of map 12, a handpiece being under dualcontrol is shown by its associated button being half one color and halfthe second color.

The surgeon then indicates what footswitch assignments are wanted forthe present operation, step 172 of FIG. 11. This step is performed bydepressing the touch screen image of each legend 168 a, 168 b or 168 cof each handpiece 34 that is to be mapped to a new footswitch assembly44. Upon each depression of the legend image, display controller 64changes the footswitch mapping for the handpiece. Specifically, thedisplay controller cycles the mapping through the following sequence:footswitch assembly associated with upper socket 48; footswitch assemblyassociated with lower socket 48; dual control mode; and no footswitchcontrol. As the mapping changes, the color of the button 170 a, 170 b,or 170 c changes appropriately to indicate the new assignment for theassociated handpiece.

As mentioned above, it is possible to separate a handpiece 34 fromfootswitch control. This option may be selected for example, when thesurgeon chooses to use a handpiece mounted switch to regulate theactuation of the handpiece 34. When this option is selected, theassociated button 170 a, 170 b or 170 c on map 162 is presented as agrey. Acceptance of specific footswitch assembly assignment map isperformed depressing the image of the accept (ACPT) button A23 alsopresented of the image of map 162.

It should be understood that the footswitch assignment mapping can onlybe performed by pressing buttons presented on display 42. This preventsinadvertent depression of the footswitch pedals for unintentionallyserving to transfer control of a handpiece 34 from one footswitchassembly 44 to the second footswitch assembly 44.

In response to the surgeon performing step 172, display controller, instep 174 maps the new footswitch assignments into the footswitchassignment tables 1504 The surgeon(s) is(are) then able to use actuateeach handpiece 34 by depressing the appropriate pedal on the footswitchassembly 44 assigned to control that handpiece, step 176.

In order to allow operating room personnel to readily keep track ofwhich, if any, footswitch assembly 44 controls a specific handpiece 34,information about this relationship is presented on the run time display178, depicted in FIG. 13. Specifically, a bar 180 is presented for eachhandpiece connected to control console. Integral with each bar 180 is alegend 182 that identifies the handpiece. On the right side of the bar180 a footswitch icon 184 appears if the handpiece is under footswitchcontrol. The color of the icon 184 identifies the footswitch assembly 44controlling the handpiece 34. In FIG. 13, a green icon 184 is presentedwith the 10 mm bur bar 180. This means the green footswitch assembly 44controls this instrument. Both a green icon 184 and a yellow icon 184are presented with the bar associated with the reciprocating saw bar180. This means that this instrument is in the below described dualcontrol mode. However, one icon 184 is displayed at full brightness,here the yellow icon; the second icon, here the green icon 184, isdisplayed at reduced brightness (represented by the phantompresentation). This means that at, the present instant, the yellowfootswitch assembly has control of the saw.

In FIG. 13 there is no footswitch icon within the 5 mm drill bar 180.This serves as indication this handpiece 34 is not under the control ofeither footswitch assembly 44.

Once the desired footswitch assembly 44 assignment maps have beenentered into the control console 32, the surgeons can then perform theprocedure, represented by step 186

During the course of a surgical procedure, there may be movement of thesurgeons, handing off of the handpieces 34 between surgeons or movementof the footswitch assemblies 44. As a result of any one of these events,there may be confusion regarding which surgeon is using which footswitchassembly 44 to control which handpiece 34. If this confusion arises,surgeons can easily place the handpieces in an up position, away fromthe patient, and actuate each handpiece. As each handpiece is actuated,the run time image changes to show which handpiece is running. Thisprovides the surgeons with a quick means to determine which footswitchassembly 44 is controlling which handpiece 34.

Once the operation begins, the map assignments for the footswitchassemblies 44 may be changed as represented by step 188. Specifically,by depressing other buttons presented on display 42, it is possible tohave display controller 64 represent the image of the footswitchassignment map 162. The new footswitch assembly 44 assignments are thenentered. These assignments are then mapped into the footswitchassignment tables 150, step 190. System 10, with the new footswitchassemblies assignments, is again available for use.

As mentioned above whether the system is in either the plug and playmode or the multiples mode, there may beta situation when one or more ofthe handpieces 34 are placed in the dual control mode. When a handpiece34 is in this mode, the depression of an assigned foot pedal on eitherfootswitch assembly 44 will actuate the handpiece. When a handpiece 34is in this mode, display controller 64 executes the process steps ofFIG. 14 to prevent both footswitch assemblies 44 from simultaneouslycontrolling the handpiece. Initially as represented by step 194, displaycontroller 64.monitors the output signals from both footswitchassemblies 44 to determine if either assembly actuates a handpiece underdual control.

If, in step 194, an actuation signal is received from either footswitchassembly 44, display controller 64 instructs motor controller 86 toactuate the handpiece, step 196. Also in step 196, the run time displayA26 is changed so as to brighten the image of the icon 184 associatedwith the activating footswitch assembly 44.

The surgeon using the actuating footswitch assembly 44 may then pressthe pedals so as to instruct the control console 32 to turn off thehandpiece 34. If this event occurs, the display controller causes thehandpiece to be deactived. The display controller 64 returns to step194. (Above steps not shown.)

However, during step 196, the surgeon operating the second footswitchassembly 44 may attempt to turn the handpiece on, as represented by step198. Display controller 64 ignores this signal. Instead, as representedby step 202, display controller waits to receive from the firstfootswitch assembly signals indicating the handpiece is to be turnedoff. Upon receipt of this signal, in step 204, display controller 64turns of the handpiece. Display controller 64 takes this action eventhough the second footswitch assembly is still generating a commandcalling for the handpiece to be actuated. Also as part of step 204,display controller dims the intensity of the icon 184 associated withthe actuating footswitch assembly 44. At this time both footswitch icons32 associated with the handpiece under dual control are in dim state.This provides operating room personnel with an indication that, at thepresent time, neither footswitch assembly 44 has control of thehandpiece 32.

Instead, as represented by step 206, waits to receive a signal from thesecond footswitch assembly 44 to turn off the handpiece 34. Until thissignal is received, display controller 64 prohibits either footswitchassembly 44 from actuating the handpiece 34.

Once, in step 206, a signal is received from the second footswitchassembly to turn off the handpiece, display controller is able toexecute step 208. In step 204, display controller again monitors theoutput signals from both footswitch assemblies 44 to determine if eitherof them have turned on the handpiece 34. Thus, step 208 is essentiallyidentical to first described step 194. Once this type of signal isreceived, display controller 64 reexcutes step 196 to reactuate thehandpiece 34.

Motor controller 86 is now generally described by reference to FIGS. 15Aand 15B. Specifically, the motor controller 84 includes two identicalpower driver and sense circuits 210. Each power driver and sense circuit210 is capable of supply the power to the motor 36 of any handpiece 34connected to any one of the sockets 40. (In FIGS. 15B and the followingfigures, the individual sockets 40 are identified as S1, S2 and S3.)Specifically, internal to each power driver and sense circuit is an Hbridge 212. The H bridge is the sub circuit that selectively ties eachwinding of the connected to either the 40 V power line or ground.

The power driver and sense circuit 210 also monitor signals generated asa consequence of the actuation of the handpiece motors. In order toperform this monitoring, each circuit 210 has a BEMF analog circuit 214The BEMF analog circuit extracts the BEMF signal produced across theunenergized winding internal to the motor. A BEMF analog to digitalcircuit 216 converts the extracted BEMF signal to a digital signal. ANISENSE analog circuit 218 monitors the currents drawn by the handpiecemotor 36 as well as currents internal to the control console 32. AnISENSE analog to digital circuit 220, also internal to circuit 210,converts the signals representative of the monitored currents intodigital signals.

The power signals, the energization signals, to the motor windingsoutput by the H bridges 212 are applied to a motor multiplexer 222.Motor multiplexer 222 is capable of generating the power signalsgenerated by H bridge 212 to any one of three sockets 40.

A motor processor 224, also part of the motor controller 86, regulatesthe operation of the power driver and sense circuits 210 and the motormultiplexer 222. In some preferred versions of the invention, a DSPprocessor is employed as the motor processor 224. One processor fromwhich motor processor 224 can be constructed is the TMS320C6713floating-point digital signal processor available from Texas Instrumentsof Dallas, Tex. Certain data used by motor processor 224 are written toand read from a flash memory 226. One such flash memory is available theIntel Corporation. Data stored in flash memory 226 include theinstructions executed by motor processor 224, configuration data for theFPGAs 228 and calibration data for the current sensing circuits.

The actual control signals generated to the power driver and sensecircuits 210 are generated by field programmable gate arrays (FPGAs)228. Each FPGA 228, in response to instructions from the motor processor224, generates control signals to a separate one of the motor driver andsense circuits 210. Each FPGA 228 also receives the digitized BEMF andsensed current signals from the circuit 210 to which the FPGA isconnected. The FPGAs 228 also control the settings of motor multiplexer222. Suitable FPGAs can be manufactured from the XC2S3x Spartan Seriesprogrammable gate arrays available from the Xilinx Corporation of SanJose, Calif.

Motor processor 224 is connected to the flash memory 226 and the FPGAs228 by a parallel bus 230. (Bus 230 shown as a single line in FIG.15A.).

The basic structure of an H bridge 212 is shown in the block andschematic diagram formed by FIGS. 16A, 16B and 16C. By point ofreference a stator 232 of a handpiece motor 36 to which the energizationsignals are applied is illustrated in FIG. 17. Stator 232 has threewindings 234 that are tied to a common center point 236. The individualwinding terminals that are tied to the 40 V power line, ground, or theBEMF analog circuit 214, are identified as M1, M2 and M3.

In FIG. 17, the depicted winding arrangement is of a wye-connectedmotor. It should be appreciated that system 10 of this invention canalos be used to regulate the actuation of delta-connected motors.

The 40 V power signal is received by a transient protection circuit 238internal to the H bridge 212. Transient protection circuit 238selectively inhibits the outputting of the 40 V signal to prevent anybraking transient signals from one winding 234 from glitching over to asecond winding. Internal to the transient protection circuit is a FET(not illustrated) that controls the outputting of the 40 V signal. ThisFET is gated by a control signal from the complementary FPGA 228(connection not shown). The 40 V power signal is output from transientprotection circuit 238 over a 40 V rail 240 internal to the H bridge.

For each winding 234, the H bridge 212 has two FETs 242 and 244, that,respectively, tie the winding terminal to the 40 V rail 240 or ground.In FIGS. 16A, 16B and 16C, the terminals tied to the winding terminalsM1, M2 and M3, are identified as M1P, M2P and M3, respectively. FET 242is tied between the 40 V rail 240 and the MxP terminal. FET 244 is tiedbetween the MxP terminal and ground. Not shown are the reverse biasedzener diodes connected across the sources and drains of FETs 242 and244, one each per FET, for voltage protection.

Each pair of FETs 242 and 244 are controlled by a FET driver 246. EachFET driver 246, in response to control signals from the complementaryFPGA 228, assert the gate signals to the complementary FETs 242 and 244.A base driver that can be used as the foundation of a FET driver is theIR218× Series High Voltage Gate Driver available from InternationalRectifier (Richardson Electronics) of LaFox, Ill. The control signalgenerated by the FET driver 246 to the gate of FET 242 is applied to thegate through a resistor 248. The FET driver monitors the voltage at thesource of the FET 242 through a resistor 250. The control signal to tiea winding 234 to ground is applied to the gate of FET 244 through aresistor 252.

A resistor 254 is connected between the source of each FET 244. Theopposed ends of each resistor 254 are tied together and connected to acommon resistor 256. The opposed end of resistor 256 is tied to ground.The voltage across each resistor 254 is measured as being a signalrepresentative across the motor winding 234 with which the resistor 254is associated. This voltage is measured off the MxIP and MxIN terminalsin FIGS. 16A, 16B and 16C. The voltage across resistor 256 is measuredas being a signal representative of the total current drawn by thehandpiece motor 36. This signal is measured across the OVRLIP andOVERLIN terminals of FIG. 16C.

One sub-circuit of the BEMF analog circuit 214 is now described byreference to FIG. 18. This particular sub-circuit is used to measure thevoltage of the power supply. Specifically, the 40 V rail signal from Hbridge 21 is applied to this circuit; the PSI terminals in FIGS. 16C and18. The signal on this circuit is tied to ground through two seriesconnected resistors 258 and 260. The divided 40 V signal at the junctionof resistors 258 and 260 is buffered by a unity gain amplifier 262. Theoutput signal for amplifier 262 is the PSV_SNS signal representative ofthe power supply voltage.

BEMF analog circuit 214 also includes the sub-circuit illustrated inFIG. 19. This is the actual sub-circuit that measures the BEMF signalsdeveloped across the motor windings 234 when they are not energized. InFIG. 19 the winding terminals are shown as being directly connected tothe circuit. In actuality, each winding terminal M1, M2 and M3 isconnected to a voltage divider and applied to a buffer amplifier. Thusthe BEMF signals are preprocessed in manner similar to how the 40 Vpower signal is processed to form the PSV_SNS signal.

Each divided and buffered winding terminal signal is applied to througha resistor 266 to the noninverting input of an amplifier 268. Alsoapplied to the noninverting terminal of each amplifier 268 is a V_REFsignal. This V_REF signal, prior to application to amplifiers 268 isbuffered by a unity gain amplifier 270. The signal from amplifier 270 toamplifier 268 is applied through a resistor 272.

Each winding terminal is also connected to a separate resistor 272. Thefree ends of the resistors 272 are tied together and applied to a unitygain buffer amplifier 274. The output signal from amplifier 274 isapplied to the inverting input of each amplifier 268. The signals to theseparate amplifiers 268 are applied through separate resistors 276. Afeedback resistor 277 is tied between the output and inverting inputterminals of each amplifier 268. Thus, amplifier 268 is used to producea recreated neutral voltage for the motor consisting of the sum of theBx_SNS signals divided by three.

The output signal of each amplifier 268 is the measure of the BEMFsignal at the winding terminal to which the amplifier is connected.These signals are represented as the B1_SNS, B2_SNS and B3_SNS signalsin the drawings. It is understood that individually each of thesesignals is representative of the voltage at the associated windingterminal minus the recreated neutral voltage for the motor 36.

Referring to FIG. 20, a detailed description of the ISENSE analogcircuit 218 is now provided. Each pair of MxIP and MxIN signals from theH bridge 212 are applied to, respectively, the noninverting andinverting inputs of separate differential amplifiers 280. The OVERLIPand OVERLIN signals are similarly applied, respectively, to thenoninverting and inverting inputs of a differential amplifier 280. Whilenot shown, it should be understood a buffered VREF signal is applied toeach noninverting input of the amplifiers 280. Individual bufferamplifiers, (not illustrated) are used to apply the buffered VREF signalto the amplifiers 280. Each amplifier 280 serves as a ×10 gain circuitfor the signal with which the amplifier is associated.

The signals from the individual amplifiers 280 are applied to a 4:1multiplexer 284. Control signal from the FPGA 228 selectively forwardone of the sensed current signals for further processing. The selectedsignal is forwarded from multiplexer 284 to a variable gain amplifier286. In one version of the invention, amplifier 286 has a variable gainfrom 1 to 20. Amplifier 286 is a digital amplifier such that the gaincan be adjusted in 256 steps. The command signals for establishing thegain of amplifier 286 come from the FPGA 228.

The output signal from amplifier 280 to which the OVERLIP and OVERLINsignals are applied is also applied to a gain and average circuit 288.This circuit multiplies the total motor current sensed circuit by 2.Circuit 288 also averages the signal over a select period, for example 1millisecond. The output signal from gain and average circuit 288 isoutput as an average power drawn signal (PSI_SNS).

The BEMF analog circuit 216 is now described by reference to FIG. 21.Circuit 216 includes a 5:1 multiplexer 292. Three input signals tomultiplexer 292 are the three Bx_SNS BEMF signals from the BEMF analogcircuit 214. A fourth input to multiplexer 292 is the PSV_SNS signalfrom buffer 262 representative of the power supply voltage. Theremaining input to the multiplexer 292 is the PSI_SNS signal from gainand average circuit 288 representative of power supply current. Acontrol signal from the FPGA 228 selects one of the five signals forfurther processing.

The signal selected by processing is output from multiplexer 292 to ahigh speed DC accurate buffer amplifier 294. Not illustrated is thefeedback resistor tied between the output and inverting input ofamplifier 294. Also not illustrated are the voltage limit diodes thatare reverse biased tied to the output of amplifier 294. A first diode istied between the amplifier 294 and the 5 Volt analog bus. A second diodeis reverse bias tied between the output of amplifier 294 and ground.

The signal produced by amplifier 294 is applied to an analog-to-digitalconverter 296. The output signal from converter 296 is supplied to theFPGA 228.

The ISENSE analog to digital converter circuit 220 is illustrated inFIG. 22. The output signal from variable gain amplifier 286 is appliedto a high speed buffer amplifier 298. Amplifier 298 and its supportingcomponents, a feedback resistor and voltage limit diodes (components notillustrated) are similar to those attached to buffer amplifier 294. Theoutput signal from buffer amplifier 298 is applied to an analog todigital converter 300. The output signal from converter 300 is appliedto the FPGA 228.

Motor multiplexer 222 consists of six relay circuits 302, one of whichis illustrated in FIG. 23. Each relay circuit receives a separate MxPsignal. Three relay circuits 302 receive the M1P, M2P and M3P signalsfrom one H bridge 212. The remaining relay circuits 302 receive the M1P,M2P and M3P signals from the second H bridge 212.

Each relay circuit 302 includes a first relay 304 and a second relay306. The Mx signal is applied as input to relay 304. Relay 304selectively applies the MxP signal to either one of the sockets 40, S3in FIG. 23, or to relay 306. Relay 306 selectively applies the MxPsignal to one of the remaining sockets 40, S1 or S2 in FIG. 23. Thestates of the relays 304 and 306 are regulated by control signals fromthe FPGA 228. These control signals are each applied to a FET 308. EachFET 308, controls the application of the 40 V signal to solenoid of therelay 304 or 306 with which the FET is associated. The 40 V signal isapplied to each FET 308 through a resistor 309. The signal present atthe drain of each FET 308 is applied to ground through two seriesconnected resistors 310 and 312. The signals present at the resistor 310and 312 junctions are applied back to the FPGA 228. The FPGA 228 usesthese returned signals as status signals to verify the state of therelay circuits

it should also be appreciated that only a pair of control signals fromeach FPGA 228 control the setting of the three relay circuits 302 thatcomplement the specific FPGA. Similarly, only two status signals for thethree relay circuits are returned to the FPGA 228.

Display controller 64 and motor processor 224 exchange signals over SPIbus 88. As part of the process of maintaining overall control of system30 of this invention, display controller 64 maintains a power driverassignment table 320, FIG. 24. Internal to table 32 are two power driverassignment fields 322. Each power drive assignment field 322 isassociated with a separate one power driver and sense circuits 210. Thedata in each field 322 indicates whether or not the associated powerdriver and sense circuit 210 is being used to energize a particularhandpiece 34.

When the surgeon actuates one of the handpieces, display controllerreads the data in the power driver assignment fields 322. Base on thesedata, display controller determines whether or not one of the powerdriver and sense circuits 210 is available to supply the energizationsignals to the handpiece 34. If one of the circuits 210 is available,the circuit is assigned to handpiece. Display controller 64 rewrites thedata into the power driver assignment table 320 to indicate to whichhandpiece the newly assigned power driver circuit 210 has been assigned.

Display controller 64 also sends an initialization packet to motorprocessor 224. This packet contains data identifying which of the powerdriver and sense circuits 210 has been assigned to a handpiece 34. Thetypes of data contained in the initialization data packet are discussedbelow.

FIGS. 32A and 32B collectively illustrated the control processesexecuted by motor controller 224 and an FPGA 228 to regulate theapplication of energization signals to the windings 234 of an attachedhandpiece motor 36. FIG. 32A illustrates the processes run of the motorprocessor 224. The processes run of the FPGA 228 are illustrated in FIG.32B. Generally it should be understood that the goal of these processesis to generate six (6) driver signals, one to each of the FETs 242 and244 internal to H bridge 212. The turning on and off of FETs 242 and 244is what causes current flow through the selected pair of windings at theselected chop rate.

One process module internal to the FPGA 228 is a FET driver logic module390. Module 390 is the module internal to the FPGA that generates thesignals to gate FETs 242 and 244. In FIG. 32B this is represented by thesix conductors that extend from the FET driver logic module 390 to the Hbridge. In order to minimize confusion, subsequent discussed connectionsare illustrated with only a single line conductor even when multipleconductors are present. Also, it should be recognized that many of thesubsequent discussed connections are within the same integrated circuitcomponent.

The input signals to the FET driver logic module 390 are the instructionsignals used to regulate the commutation of the windings and the drivingof the windings. The commutation instruction signals inform FET driverlogic module 390 across which pair of windings the energization signalsshould be applied. The drive signals inform FET driver logic module 390of what the PWM rate and on duty cycle should be for the energizationsignals. Based on these instructions, module 390 generates the gatesignals to turn FETs 242 and 244 off in an appropriate sequence.

The commutation instruction signals are generated by a commutation logicmodule 392 also internal to FPGA 228. Module 392, receives as inputsignals indicating the angular position of the motor rotor. Based onthese signals, commutation logic module 392 generates the commutationinstruction signals to FET driver logic module 390.

In the system of this invention, there are two alternative processes bywhich motor rotor position is determined. Internal to the FPGA 228 is aBEMF monitor module 394. Module 394 receives as input the digitzed BEMFsignals from the BEMF analog to digital converter 216. In FIG. 32B,these signals are represented as Bx_SNS signals. Based on these signals,the BEMF module 394 determines rotor position. Module 394 provides thisinformation to the commutation and logic module 392.

As discussed below, when the handpiece motor 36 is operating at a lowspeeds, the BEMF signals cannot be used to determine rotor position.Thus, when the handpiece 34 is in this state, control console uses thesecond method of determining rotor position inducatance sensing.Inductance sensing is performed by an inductance sensing (IS) monitormodule 396 internal to the motor processor 224. Generally, it should beunderstood that in inductance sensing, current through the windings 234is measured to determine rotor position. The inputs signals into the ISmonitor module 396 are measurements of the captured peaks of themeasured current flows through the individual windings 234. These peaksare captured by a IS peak capture module 395 located in the FPGA 228.The input signals into module 395 are the digitized current measurementsignals from the individual windings. It should be appreciated that, ininductance sensing mode, the current across resistor 256 is the currentthat is measured.

These currents are proportional to the voltages across resistors 254 ofthe H bridge. Digitzed representations of these signals are passed fromthe ISENSE analog to digital circuit 220 are passed from the FPGA 228 tothe motor processor 224, connection not shown. A discussion of howinductance sensing processes are used to determine rotor position is setforth below. The rotor position determinations made by inductancesensing monitor module 396 are provided to the commutation logic module392.

It should further be appreciated that motor controller 224 determineswhen the commutation logic module 392 should rely on BEMF senseddeterminations of rotor position and when the module 392 should rely onthe inductance sensed determinations. Motor processor 224 makes thisdetermination based on the actual speed of the handpiece motor and speedcutoff data from the handpiece NOVRAM 72. This cutoff data, the field inwhich it is stored not shown, indicates below what speed inductancesensed rotor position determinations are used to regulate commutation.This cut off speed is supplied to the motor processor 224 as part of theinitialization packet. Thus while the input connections are not show, itshould be further understood that inductance sensing monitor module 396also receives an indication of motor speed and the cutoff speed toperform the required comparison.

It should further be understood that inductance sensing monitor module396 also communicates with BEMF module 394, connection not shownSpecifically, inductance sensing monitor module 396 provides the initialstart logic data to the BEMF module 394 that module 394 needs to performBEMF monitoring of rotor position.

Three basic input variables are used to cause the windings to be driven.One input is based on the difference between the actual anduser-selected speed for the handpiece motor. A second input is based onthe current drawn by the motor 36. The third input is based on theoverall power that is, at any given instant, being consumed by thesystem 10.

The digitized BEMF signals, the Bx_SNS signals in FIG. 32B are what isused by the FPGA 228 to determine raw speed of the handpiece motor 36.Specifically, internal to the FPGA 228 is a speed calculator module 398.Speed calculator module 398, receives the output commutation instructionsignals from the commutation logic module 392, connection H in FIG. 32B.Based on the times between the commutations as designated by thesesignals, speed calculator module 398 generates a digital representationof rotor speed. This speed value is filterd by an FIR filter 402internal to the FPGA. The coefficients for this filter from thehandpiece NOVRAM 72 are contained in the initialization packet. (Itshould likewise be appreciated, the filter coefficients for all filtersin the DSP 224 and FPGA 228 come from the NOVRAM 72 in theinitialization packet.

The filtered speed signal is forwarded from the FPGA 228 to an IIRfilter 404. The filtered signal IIR filter 404 is applied as one inputvariable to a speed control (SC) proportional integral derivative (PID)algorithm module 406.

The second variable into the SC PID module 406 is a user speed set-pointsignal. This signal is generally a digital representation of the userselected speed for the handpiece. This signal is provided by displaycontroller 64 in both the initialization packet and in speed set-pointpackets. These speed set-packets are repeatedly sent by the displaycontroller 86 to motor processor 224 as long as the handpiece remainsactuated. Each speed set-point contains data identifying the handpiece34 with which the packet is associated and data indicating the user-setspeed for the handpiece 34. These latter data are determined by thedisplay controller by reference to the input device the surgeon actuatesto change motor speed. While a handpiece remains actuated, displaycontroller 64 typically sends a speed set-point packet once every 10milliseconds.

Prior to the speed set-point signal being received by the SC PID module406, the signal may be processed by an acceleration control module 408.This is because over time, the speed set-point signal will change as aresult of the surgeon speeding up, slowing down, or braking thehandpiece motor 36. Depending of the rate of change of the actual speedset-point signal, acceleration control module 408 adjusts the rate atwhich the set-point signal applied to the SC PID module 406 actuallychanges. This is done to minimize any jerking or other uneven operationof the handpiece motor 34 that may occur as a result of rapidacceleration, deceleration or braking.

It should be recognized that the parameters the acceleration controlmodule uses to modify the rate of change of the speed set-point signalcome from the handpiece NOVRAM 72 in the initialization packet.

The SC PID module 406, based on the difference between the actual(filtered) motor speed and the speed indicated by the set-point signaldetermines an SC PID output signal. The algorithm by which this signalis generated is made is known in the art.

While there are two constantly changing inputs into the SC PID module406, it should be appreciated that there are other variables into thealgorithm. These variables include, proportional gain, integral gainderivative, gain and derivative time constant, output max and outputmin. These variables, which are essentially constant, are supplied fromthe handpiece NOVRAM 72 by the initialization packet. For some motors,different sets of these variables are employed for speed controlpurposes at different speed ranges. The multiple sets of variables aresupplied in the initialization packet. Based on the current speed rangein which the handpiece motor 36 is operating, motor processor 224 loadsthe appropriate set of variables into the SC PID module 406.

The above mentioned constant-over-speed range variables are alsosupplied to a current control (IC) PID module 414. It should beappreciated that the set of variables applied to the SP PID and IC PIDmodules 406 and 414, respectively, are different.

The SC PID output signal from module 406 is applied to an SC outputcalculation module 409. A second input into module 408 is a motor PWMfrequency. This variable is from the handpiece NOVRAM 72 and is suppliedin the initialization packet. Based on these inputs, SC outputcalculation module 409 determines two values, the PWM period and the PWMon time for the drive signal.

Output signals representative of the values produced by the SC outputcalculation module are forwarded to a SC pulse generator 410 internal tothe FPGA 228. The SC pulse generator 410, based on the inputs frommodule 409 produces a train of speed control-based PWM drive pulses.

The current based drive signals are based on both a current set-pointfor the handpiece motor 36 and the actual current drawn by the motor. Atorque map module 412 produces the current set-point value. The threevariable form which the current set-point are determined are, the speedof the motor, a torque map and a constant. Torque map module 412receives the filtered speed signal from the FPGA FIR 402. The torque mapis a relationship specific to the motor of the torque the motor candevelop at a specific speed. The constant converts the speed-basedtorque into a current set-point. The data for the torque may and theconstant are from the NOVRAM 72 and contained in the initializationpacket.

Thus, for a given speed, based on the torque map, module 412 determinesthe torque the motor should developed. Based on this determination andthe constant, module 412 determines the current the motor should draw.Torque map module 412 supplies data representative of this currentset-point to the IC PID 414 algorithm module.

The second continually varying input into the IC PID module 414 is theactual current drawn by the motor. The current measurement supplied tomodule 414 is based on the interleaved individual winding currentmeasurements from across resistors 254 of the H bridge 212, the MxIsignals in FIG. 32B. These signals are supplied to a two stage variablefrequency filter 416 in the FPGA 228. Filter 228 removes the highfrequency ripple in this current signal to commutation switching.

The filtered current signal from filter 228 is applied to a currentcalibration module 418 internal to the motor processor 224. Currentcalibration module 418 calibrates the current for subsequent processing.A variable module 418 employs to determine the extent the current drawnsignal needs to be calibrated is the value indicating the extent theanalog version of the current signal was amplified by variable gainamplifier 286. This value, as well as the setting for amplifier 286 arefrom the handpiece NOVRAM 72 and contained in the initialization packet.

The calibrated current reading is filtered by an IIR 420 also in themotor processor 224. The filtered sensed current is applied to the ICPID module 414 as the second variable.

Based on the current set point and the filtered and calibratedmeasurement of actual current, the IC PID module produces a midpointcurrent value. The midpoint current value is forwarded to a currentcontrol output calculation module 416. From the initialization packet,module 416 previously received current range window data. These dataindicate a range between which the motor should oscillate. Based onthese window range data and the midpoint current value, current controloutput calculation modulation produces ILIMITH (high) and ILIMITL (low)current limits. It should be appreciated that the midpoint current valueis between these current limits. The range between the limits is basedon the range data in the initialization packet.

The motor processor 224 provides the ILIMITH and ILIMITL values to acurrent control limit pulse generator 419 internal to the FPGA.Generator 419 receives as another input a measure of the actual motorcurrent. In actuality the interleaved digitized versions of the threewinding currents, the digitized MxI current signals are applied togenerator 419. Based on the ILIMITx values and the measured current,current control limit pulse generator 419, based on a bang-bang process,selectively clocks out current control drive pulses.

The speed control-based PWM drive pulses from the SC pulse generator 410and the current control drive pulses from the current control limitpulse generator 419 are two of the signals used to control thegeneration of driving of the windings 234. The third input signal is apower supply limit (PSI_LMT) signal. As discussed below, this signal isasserted when the components of system 10 consume more power than theconsole power supply 90 can provide.

These three signals are applied to an AND logic module 422 internal tothe FPGA 228. The output from module 422 is applied to FET driver logicmodule 390 as the signal to drive the windings 234. AND logic module 422is configured to assert the signal to drive the windings 234 only whenthe speed control-based PWM drive pulses and the current control drivepulses simultaneous indicate the windings are to be driven and the powerlimit exceeded signal is not asserted.

It should be recognized that a feature of the above assembly is that itprovides for precise torque control of the operation of a handpiece 34.Specifically, by entering the appropriate commands, display controller64 is directed to present on display 42 torque control setting images.By pressing the touch screen buttons associated with these images, thesurgeon established the maximum torque the handpiece motor is todevelop. This is useful because for certain procedures, such as thedriving in of a implant into tissue, only a select maximum amount oftorque should be applied. Once the surgeon establishes this torquelimit, data regarding its value is provided by display controller 64 tomotor controller 224 in the initialization packet. Based on these data,motor processor 224 configures the torque map module 412 to ensure thatthe module never generates a signal indicating that the handpiece motor36 should produce more torque than the defined maximum amount.

An understanding of when and how the power supply limit signal isasserted can be obtained by initial reference to FIG. 33. Initially itshould be understood that the reason a means for power limiting isprovided is that there may be times when surgeons may attempt tosimultaneously drive two instruments that collectively consume morepower than control console 32 can provide. This is because amount ofpower any power supply can provide is invariably limited. By way ofexample, it should be understood that in some versions of the inventionit is anticipated power supply 90 provides up to 400 Watts of power. Forreasons of size and to minimize the amount of heat emitted by thecontrol console 32, it is often considered reasonable designconsideration to so limit the amount of power the control console canprovide. Moreover, there are seldom instances when both handpieces beingsimultaneously driven by the control console will need more than 400Watts of power. Therefore, it should be appreciated that is not anefficient use of resources to provide a power supply that could supplymore power.

However, there may occasionally be instances when two high-powerconsuming handpieces 34 are simultaneously connected to and energized bythe control console 32. The power supply limit circuit of system 10 ofthis invention allows both handpieces to be so actuated.

As seen by reference to FIG. 33, the power supply limit circuit includesa resistor 424 connected to the ground out of the power supply acrosswhich the current out of the power supply 40 is measured. The voltageacross resistor 424 is gain and average circuit 426, multipled andaveraged. In one version of the invention, this current drawn signal ismultipled by 20 and averaged over 1 microsecond.

The multiplied and averaged power supply current signal from circuit 426is applied to a comparator 428. The second input to comparator 428 is areference signal, not shown representative of the maximum current thepower should draw. The power is provided to the handpieces in the formof a 40 volt potential. Therefore, the maximum current the power supplyshould draw to ensure that it does not consume more than 400 Watts is 10Amps. In actuality, the power supply 90 is capable of consuming up to500 Watts, the additional however is used by the internal consolecomponents such as pump motor 60. Performing the power limit monitoringat a level less than power supply's actual power limit, essentiallyeliminates the likelihood the power supply could consume so much powerthere could be component failure.

Thus, comparator 428 continual monitors the adjusted power supplycurrent to determine whether or not the power supply is consuming toomuch current. If this condition occurs, comparator 428 asserts thePSI_LMT signal.

The PSI_LMT signal is applied to both FPGAs 228. As part of the overallprocess of regulating the energization of the handpiece motors 36, motorprocessor 224 continually determines which motor, in view of the powerlimit being exceeded, should temporarily be deactuated. Thisdetermination is made by a power supply current (PSI) limit selectmodule 430 internal to the motor processor 224. The inputs into module430 are values of the current presently being drawn by each handpiecemotor 36. Specifically these are current drawn measurements through theH bridge resistors 256. In FIG. 32A this is depicted by a single OVERLIsignal directly into module 430. In actuality it is understood thatdigitized forms of these motor current signals are forwarded from bothFPGAs 228 to the PSI limit select module 430. By comparing thesesignals, module 430 determines which of the two actuated handpiecemotors 36 at any given instant is drawing more current, consuming morepower. The PSI limit module 430 selects this handpiece motor 36 forpotential power limited necessitated deactivation.

Specifically, PSI limit module 430 asserts a power limit enable signalto an AND logic module 432 internal to the FPGA 228 associated with theselected handpiece motor 36. The PSI_LMT signal, when asserted, issimultaneously received by the AND logic modules 432 of both FPGAs 228.Only the module 432 to which power limit enable signal has been assertedforwards the PSI_LMT signal. Specifically, this signal is forwarded toAND logic module 422. As discussed above, when AND logic module 422receives the PSI_LMT signal, module 422 inhibits the assertion of thedrive signals to FET driver logic 390.

Thus the assertion of the PSI_LMT signal causes the enabled FPGA 228 totemporarily stop asserting drive signals. This stops the application ofenergization signal across the windings of the motor 36. Thus the motoris forced to temporarily coast. This does prevent the power supply 90from consuming more than the amount of power it is designed to consume.

As discussed above, at normal operating speeds, the FPGA 228 associatedwith the driver power driver and sense circuit 210, regulates thecommutation switching of the motor windings 234 by monitoring the BEMFsignals generated across the unenergized motor winding 234. However, atlow speeds, speeds 10% or below of the maximum operating speed of thehandpiece motor 36, and for some handpieces, speeds 5% or below the BEMFsignal across a winding drops to a level at which it cannot be detected.

When this event occurs, motor controller 86 employs inductance sensingto determine the position of the motor rotor. More particularly, as seenin FIG. 27 internal to handpiece NOVRAM 72 there is a BEMF/IS set pointfield 339. Field 339 contains data that indicates the speed above whichmotor controller 86 should employ BEMF sensing to determine rotorposition. At speeds at or below the speed set forth in field 339, motorcontroller 86 employs the below-described inductive sensing process todetermine rotor position. The speed level in the BEMF/IS set point fieldis supplied by display controller 64 to the motor processor 224 in theinitialization packet. Based on the data indicating motor speed and thevalue from field 339, motor processor 224 selectively uses BEMF sensingor inductive sensing to regulate the energization of the handpiece motor36.

The motor controller 86 starts the inductive sensing process bymeasuring the inductance across the windings in each of the six motorphases. This is performed by first negating the application ofenergization signals to the windings 234 as represented by time period336 in the plot of FIG. 25.

Then, during time period, short voltage pulses are applied across eachmotor winding 234. In order to measure inductance in a first phase, oneof the windings is tied to the 40 V rail 240 of the H bridge 212, theremaining two windings are tied to ground. The current developed by thewinding connected to the 40 V rail 240 is then measured. To measureinductance in a second phase opposite the first phase, the two windingsthe power connections of the windings are reversed. Thus, the twowindings just tied to ground are connected to the 40 V rail 240; thewinding 234 attached to the rail is tied to ground. Current through theground tied winding is then measured. These measurements are made forall three windings 234. Thus as depicted in FIG. 25, there are sixmeasured current pulses 338 from the motor 36.

In theory, for any given position of the motor rotor, the measuredcurrent for one of the motor phases should be higher than measuredcurrent for the remaining five phase measurements. This is because theposition of the rotor magnets affects the inductance across the windingsand therefore, the current through windings.

However, as indicated by reference to the graph of FIG. 26, inactuality, it has been found that for the DC motors of surgicalhandpieces 34, there is a poor correlation of measured inductance torotor position. It is believed this poor correlation is due to the factthat the handpieces 34 integral with system 30 of this invention havemotors 36 with relatively small rotors. In particular the rotorstypically are 0.5 inches or ess in diameter. Still other of the motorrotors have diameters of 0.25 inches or less. Due to the relativelysmall size of the magnets integral with these rotors, the magnets do notchange the inductance of the adjacent motor windings 234 to the degreeat which inductance changes alone can be used to determine rotorposition.

Thus, in system 30 of this motor processor 224 applies gain and offsetvalues to the measured motor phase currents. These gain and offsetvalues come from data fields 340 and 342, illustrated in FIG. 27, withinhandpiece NOVRAM 72. Specifically, for each rotor position, NOVRAM 72contains data in field 340 that includes the coefficient for multiplyingthe measured current, to produce the gain. Data in each field 342contains a constant that is applied to the multiplied gain, the offset.These data, as well as the data in the BEMF/IS speed set point field 339are forwarded from display controller 64 to motor processor 224 as partof the initialization packet.

It should be understood that for each type of motor 36, the gain andoffset values for fields 340 and 342, respectively, are developed byempirical analysis of the operation of the motor.

Based on these retrieved gain and offset data, motor processor 224 isable to produced a calibrated, normalized current measurement for eachcurrent value. As seen by reference to FIG. 28, these calibratednormalized values result in a plot wherein for each rotor position asingle one of the current values is higher than the other currentvalues.

Thus based on these calibrated and normalized measurements of windinginductance, motor processor 228 is able to determine the position of themotor rotor. Based on this determination, motor processor 228 is able todetermine through which windings 234 current should next be applied.This is represented in FIG. 25 by period 346 an energization signal isapplied to across the appropriate two of the motor windings 234. It willbe noted also from this figure that a quiescent period 350 that proceedsperiod 336 so the current measurements can made. Collectively, periods336 and 350 are approximately 10% of the size of period 346 in which asignal is applied to a single winding pair to actuate the motor.Generally the combined period for a single cycle of periods 336, 346 and350 is 1 millisecond.

It should be recognized that this use of inductance measurement sensingto monitor rotor position and regulate the energization of windings canbe used in situations other than when the handpiece motor 36 isoperating in a low speed state. This inductance measurement sensing canbe used to regulate winding energization even when the motor is stopped,a 0 RPM speed. Thus, inductance measurement sensing can be used toregulate motor start up when the handpiece is initially actuated.Inductance measurement sensing can also be used to regulate motoractuation when as a result of the motor developing an amount of torquethat approaches or equals the maximum torque it can develop the motorrotor slows to a very low speed or even stops.

A step in the inductance sensing of rotor position that is alsopracticed involves commutation state calculation. Specifically, in thesystem 30 of this invention, motor processor 224 does more than basecommutation state on a calibrated and normalized measure of motor phaseinductance. Motor processor also reviews whether or not after one givencommutation phase in inductance sensing is determined, the nextdetermined phase is appropriate. Based on this determination, motorprocessor then places the motor 36 in the next appropriate commutationstate. This process can be understood by reference to the flow chart ofFIG. 29. Step 350, represents the transition from one peak sensedinductive current phase to a second peak sensed inductive current phase.After this transition occurs, in step 352, motor processor 224determines whether or not the second peak sensed inductive current phaseis one that is immediately adjacent the previously determined first peaksensed inductive current phase. By way of example to the calibrated andnormalized peak currents of FIG. 28, if the immediate past current phasewas the M3 Negative phase, than the immediately adjacent phases are theM2 Positive and M1 Positive phases. In step 352 if the sensed phase isfrom one of these two phases, it is assumed that motor is workingproperly. Then, in step 354, motor processor 224 instructs theappropriate FPGA 228 to make the next appropriate commutation shift ofthe energization signals applied to the windings.

However, in step 352 it may be determined, for example, that immediatelyafter the M3 Negative sensed inductive current phase is highest, thenext sensed highest inductive current is from the M3 Positive phase.This is because due to manufacturing tolerances, during the transitionbetween the from M3 Negative and the M1 Positive phases being highest,the inductive sensed current corresponding to the M3 Positive phase ishighest.

In response to this determination, in step 356, motor processor 224determines whether or not the peak inductive sensed current for this newphase is reaches a level that is significantly higher than level for atwhich the phase transition between sensed currents occurs. In presentexample, motor processor 224 would only switch from motor driving basedon the M3 Negative sensed phase to driving based on the rotor being inthe M3 Positive phase, if the normalized inductive sensed current forthe M3 Positive phase exceeds that of the last measured M3 Negativephase by a value of 0.5.

If, in step 356, it is determined that the apparently out of sequenceinductance measurement is appreciably higher than the preceedingmeasurement, the measurement is accepted as accurate. Step 354 isexecuted. In this version of step 354, motor processor 224 instructs theappropriate FPGA 228 to make the next appropriate commutation shift ofthe energization signals based on the motor being in the detected phase.

Alternatively, in step 356 it may be determined that the apparently outof sequence inductive measurement is below this threshold value. If thisdetermination is made, this highest determined inductive sensed phase isignored. Instead, step 350 is reexecuted. In this, and in all executionsof steps 350 and 352, inductance sensing monitor module 396 basis itsdetermination on whether or not there has been a change in motor phasewhen the next expected phase is only marginally higher than the presentphase. In the present example, the calibrated and normalized inductancesensed signal for the expected M1 Positive stage only has to be 0.1higher than that of the present phase, the M3 Negative phase, for themotor processor 224 to determine that the motor rotor is now in aposition corresponding to the M1 Positive phase.

In step 356 it may be determined that the out-of-sequence inductancesensed measurement is appreciably higher than the value of theinductance sensed measurement of the last phase. This “last phaseinducatance sensed value” is from the crossing of the two inductancesensed signals. If this event occurs, it is interpreted by motorprocessor 224 as meaning that the motor rotor is actually in theposition indicated by this new highest inductance sensed measurement. Inthis event, motor processor applies energization signals to the motorwindings based on this new determination of rotor position.

An advantage of this feature of system 30 of this invention is that itessentially eliminates the likelihood that small out-of-sequencedeterminations of next highest motor phase that occur because ofoperation glitches and motor winding variations do not cause the motorcontroller 86 to incorrectly energize the windings based on erroneousdeterminations of rotor position.

Motor processor 224 of this invention further configured to adjust thegain and offset constants for the motor phases. Specifically asindicated by the flow chart of FIG. 30, in step 362 motor processor 224determines, for each motor phase, whether or not, for a rotation of therotor, the calibrated and normalized inductance sensed measurements arewithin a predefined window. This window can, for example be between −0.1and 1.1. If in step 362 it is determined that the calibrated and sensedinductance sensed measurements for the phase are in this range, norecalibration is performed.

However, in step 362 it may be determined that the calibrated andnormalized inductance sensed measurement is outside of the definedwindow. If this state is detected, in step 364, motor processor 224performs adjustments of the gain and offset coefficients. Theseadjustments are performed iteratively until, in a subsequent executionof step 362 it is determined that the calibrated and normalizedinductance sensed measurements for the motor phase are within thedefined window.

This feature of the invention ensures that shifts of the inductancewaveforms over time due to changes in temperature and component wear donot result in incorrect motor states from being calculated.

Still other methods of performing this recalibration is by locking themotor rotor in set of known positions and then taking inductancemeasurements. Recalibration is then made based on the measuredinductance. Long term averages of sensed inductance measurements canalso be employed to determine how to appropriate adjust the gain andoffset values.

In some versions of the invention, display controller 64, through theNOVRAM interface 78 writes the recalculated gain and offset values fromthe motor phases into the handpiece EEPROM. These data are then read bythe display calculator and used the next time the handpiece 34 isplugged into the control console.

In practice, this on the fly recalibration of the motor pole gain andoffset values may be performed as soon as the inductance sensing processis initialized. The maximum and minimum normalized sensed inductancevalues are captured. If through a rotation of the motor rotor it isdetermined the peak-to-peak normalized sensed values exceed a value of1.0 or are less than 1.0, the gain and offset values are recalculated bythe motor processor 224 for this current run of the handpiece 34.

Many handpiece motors are constructed so that when rotor position basedcontrol switches from the inductance sensing mode to the BEMF sensingmode that energization sequence for the windings remains constant. Somemotors 36 are, however, constructed so that when control shifts frombetween the inductance sensing and BEMF sensing modes, the energizationsequence of the windings is reversed. Handpiece NOVRAM 72 thus containsa data flag, represented by BEMF/IS Reverse Energization Sequence field368 in FIG. 27. The setting of this flag in field 368 indicates whetheror not motor controller 86 upon switching between BEMF sensing andinductance sensing of rotor position should reverse the energizationsequence of the windings.

Based on the setting of the flag in field 368, motor processor 224, uponchanging sensing modes selectively also reverses the sequence in whichthe windings are commutated.

The above means of inductance sensing monitoring of motor rotor positionis used to control the operation of the handpiece so the handpiece canprovide the maximum amount of torque. In an alternative method ofinductance sensing of rotor position, control console 32 is able to alsoprovide precision speed regulation of the handpiece motor to 0 RPM.

Specifically, in alternative version of this invention, a mathematicalmodel of the inductance sense signal profile for a single motor pole isdeveloped, step 372 in FIG. 31. A Fast Fourier Transformation can beused to create this model. (It is understood that not all inductancesensed signals have the sine wave profile of motor poles depicted inFIG. 28. The coefficients describing this signal profile are stored inthe handpiece NOVRAM, field 370 in FIG. 27. These data are provided tothe motor processor 224 in the initialization packet, step 374.

Upon receipt of the data, the motor processor 224 uses the datadescribing the single signal profile to develop a table indicating forevery degree of rotor position, the excepted inductance sensed signalfor each of the motor phases, step 376. When the handpiece motor is inthe inductance sensed mode, the calibrated and normalized inductancesensed signal values for each of the six motor phases are determinedfrom the measured data, step 378. These six calculated values are thenmatched to the closest set of table values, step 380. Thus, the matchingof step 380 serves to determine, based on the plural inductance sensedcalibrated and normalized values, the angular position of the motorrotor.

Steps 382 and 384 are repeats of steps 378 and 380, respectively, at alater time. Based on the difference in determined rotor position fromsteps 380 and 384 divided by the time difference, motor processor 224 isthe able in step 386 to determine rotor speed.

The above method of inductance sensed speed is employed at low speedswhere the BEMF signals typically are not strong enough to facilitateprecision speed control. Generally, low speed for this type of controlis consider a speed of 15% or lower of maximum motor speed, and moreoften a speed of 10% or lower of maximum motor speed.

The method, inductance sensing for inter-commutation rotor positiondetermination, can be used to determine rotor position for speeds downto 0 RPM.

The means by which system 10 of this invention monitors the BEMF signalsis now explained by reference to FIGS. 34A and 34B. Line segment 440 ofthe plot of FIG. 34 illustrates the theoretical rise in the BEMF signalacross the unenergized winding 234. Arbitrarily, line segment 440 can beconsidered-the monitored BEMF signal across a first winding, the B1_SNSsignal. Line segment 442 can be considered the monitored BEMF pulseacross a second winding, the B2_SNS signal. Line segment 446 can beconsidered the monitored BEMF pulse across a third winding, the B3_SNSsignal. The pattern then repeats.

In actuality, the changes in the switching of the commutation phases ofthe windings, a glitch is often present in the initial phase of a BEMFsignal because of flyback currents. This is represented in by the downvoltage glitch pulse 448 associated with line segment 442.

In order to avoid false determinations of rotor position based on theseglitches, the FPGA BEMF monitor module 394 integrates the measured BEMFsignals over time. More particularly, module 394 only integrates aparticular BEMF signal starting from the time at which the signal insone-half through its rise or fall. Thus, with regard to the signalrepresented by line segment 440, BEMF monitoring module 394 onlyintegrated the signal from the time represented by point 450. The BEMFsignal represented by line segment 442 is only integrated from the timerepresented by point 452. The BEMF signal represented by line segment444 is only integrated from the time represented by point 454.

The integrations of these BEMF signals are represented by the area underthe integration curves in FIG. 34B. The BEMF monitor module 394integrates each BEMF signal until a defined common threshold value isreached. This threshold value comes from the NOVRAM 72 in theinitialization packet. This threshold value is represented by point 458in FIG. 34B.

The time of the initial half way point for the initial BEMF signal,point 450 in FIG. 34A, comes from the commutation logic module 392.Module 392 also provides data upon which the time of second and thirdhalf way point, points 452 and 454, respectively, can be determined.

BEMF monitor module predicts when the next half way point, point 456 inFIG. 34A, according to the following process. Initially, module 394determines when the peak integration value associated with the BEMFsignal of line 440 occurs, point 458 on FIG. 34B. Then, the time atwhich the threshold value associated with the BEMF signal of line 442occurs, point 460. The time between these two events is the actual timethe BEMF signal of line 442 was at its true half way point. (For anygiven half-way time point of the BEMF signal, the difference between thepredicted time and actual time is nominal.)

BEMF monitor module 394 determines the time at which the integrationthreshold value associated with the BEMF signal of line 446 is reached,point 462. Based on the time difference between the threshold values ofpoints 460 and 462 occurred, module 394 determines the actual time, theBEMF signal of line 446 reached its half-way point. At this time BEMFmonitor module 394 has in its memory data indicating when the signal ofhalf way point 454 should have occurred and the time difference betweenwhen the half-way points of the transits of the BEMF signals of lines442 and 446. BEMF monitor module 394 adds this time difference to thetime at which the half-way transit represented by point 454 occurred.This sum is the prediction of when the BEMF signal represented by line455 will occur, point 456. The BEMF monitoring module 394 thus starts itintegration at this time.

In other versions of the invention, BEMF monitor module 394 may startintegration before or after the half-way point of the BEMF signaltransit. Generally though, switch glitches are over before this half-waypoint.

The half-way transit times of the transits of the later BEMF signals arerepeatedly calculated in this manner. Thus, when the slope of the BEMFsignals change as a result of speed changes of the handpiece motor 36,the predicted times of the half-way points of the signal's transits willsimilarly change. Thus, the half-way transit times predicted by the BEMFmonitoring module, the times at which the module starts its integrationprocess will, even with speed changes, closely approximate the truetimes.

It should be appreciated that the reason the signal is BEMF signal isintegrated, as opposed to the monitoring of the occurrence of a 0crossing, is to eliminate false determinations of motor phase due tohigh frequency noise.

FIGS. 35A and 35B collectively illustrate the structure of a handpieceinterface 70 of this invention. Interface 70 is able to connect to fourdevices integral with a handpiece 34 to which the interface isconnected. For drawing simplicity, the connection circuit to only asingle device, labeled the HP DEVX connection is shown. Interface 70 isable to transmit and receive both analog and digital signals to eachhandpiece device to which it is connected.

Handpiece interface 70 includes an interface controller 470. Onesuitable interface controller 470 can be constructed from the ATmega8microcontroller. Controller 470 has an internal analog to digitalcircuit 472 for digitizing analog signals received from the connectedhandpiece devices. Controller 470 serves as the interface between theconnected handpiece 34 and the display controller over bus 76. Analogsignals interface controller 470 outputs to any handpiece device areoutput in digital form to a digital to analog converter 474. Onesuitable converter 474 is available from the Texas InstrumentsCorporation.

Interface 70 has a precision voltage supply 476. Voltage supply 476outputs a precising 5 VDC voltage to the handpiece 34, the HP_REFsignal. This voltage is then available to any components internal to thehandpiece that may require a precision voltage. A current monitoringcircuit 478 monitors the current of the HP_REF signal. If this currentexceeds a certain level, it is assumed that there is a fault internal tothe handpiece. If this current level is detected, monitoring circuit 478forwards a fault signal to interface controller 470. Interfacecontroller 470, in turn, sends an appropriate fault message to displaycontroller 64.

Upon receipt of the fault message, display controller 64 presents anappropriate warning on display 42. Display controller 64 also inhibitsthe actuation of the handpiece 34 based on any signals generated by thehandpiece sensors, the on handpiece controls. This is because the highcurrent HP_REF signal is assumed to indicate there is malfunction withthese controls.

Handpiece interface 70 also includes a handpiece power supply 480. Powersupply 480 provides a power signal to the handpiece, the HP_PWR signal.This signal is available to any device internal to the handpiece otherthan motor 36 that may need power. Such a device may be a transmittingunit that is part of surgical navigation system.

Analog signals from the handpiece device through the HP_DEVx connectiontravel from the connection through an RC filter that includes threeseries connected resistors 482, 484 and 486. This filter also includes acapacitors 488 and 490. Capacitor 488 is tied between the junction ofresistors 482 and 484 and ground. Capacitor 490 is tied between thejunctions of resistors 484 and 486 and ground.

It is observed from FIG. 35B that the HP_DEVX connection is alsoattached to the inverting input of a buffer amplifier 492 through aresistor 494. The non-inverting input of buffer amplifier is connectedto digital to analog converter 474. When the handpiece NOVRAM 72 dataindicates analog signals are to be received from the connected device,based on instructions received from display controller 64, interfacecontroller 470 configures the circuit. Specifically interface controller470 causes digital to analog converter 474 to assert a signal to thenon-inverting input of amplifier 492 that disables the amplifer. Sincethe amplifier is out of the circuit, signal flow is solely from theHP_DEVx connection to the RC filter.

The signal from the RC filter, the signal out of resistor 486 is appliedto the controller analog to digital converter 472 for processing by thecontroller 470

In the event interface 70 is to output an analog signal to a handpiecedevice, controller 470 activates buffer amplifier 492. A digitizedversion of the signal is output from controller 470 to digital to analogconverter 474. The analog signal produced by converter 474 is applied tothe non-inverting input of buffer amplifier 492. Note a pull downresistor 496 is also tied between the non-inverting input to amplifier492 and ground.

The analog signal out of amplifier 492 is applied through a diode 498 tothe HP_DEVx connection.

Digital signals into interface 70 take the same conductive path from theHP_DEVX connection to controller 470 as the analog input signals. Whendigital signals are received, controller 470 disables its analog todigital converter 472. Consequently, the input signals are processed asdigital signals.

Digital signals transmitted by the interface are transmitted bycontroller 470 through the controller terminal through which analogsignals are normally received. The digital output signals thus passthrouh resistors 486, 484 and 482 to the HP_DEVX connection.

In FIG. 34B two zenner diodes 500 are shown reverse bias connectedbetween the 5 VDC bus and ground. The junction between diodes 500 isconnected to the junction between resistors 482 and 484. Two diodes 502are similarly series connected and reverse biased between the 5 VDC busand ground. Diodes 502 are connected at their common junction to theinverting input of buffer amplifier 492. Diodes 500 and 502 thus providevoltage protection for the interface.

In some versions of the invention a relay may be connected between theHP-DEVx connection and the interface circuit. This relay, when actuated,attaches the relay to the RFID interface 78. Thus, this relay isactuated to connect the HP_DEVx connection to the RFID interface 78 whenthe handpiece component is antenna designed to inductively exchangesignals with a RFID associated with the handpiece.

It should be recognized that another feature of system 30 of thisinvention is that the display controller 64, motor controller 224 andthe FPGAs 228 are totally reprogramable. For example, by enteringinstructions through the 1394 Interface 68, the algorithms of the PIDmodules 406 and 414 can be significantly modified. Thus, one or more ofthe motor drive and sense circuits 210 can be reset to operate in adirect drive mode or provide open loop control. Similarly, one or morethe motor drive and sense circuits 210 can be reprogrammed to supply theenergization signals to a handpiece 34 with a power consuming componentthat does not include a motor. Such handpieces include RF ablationtools, light emitting devices, electracautery devices and devices thatdrive ultrasonic tissue forming accessories.

It should therefore be appreciated that the above description isdirected to one particular version of this invention. Other versions ofthe invention may have features different than what has been described.For example, each of the above features may not be incorporated into allversions of this invention.

Also, other versions of this invention may have diifernt features. Othermeans than inductance sensing may be employed to provide thetorque-down-to-stall control of the handpiece motor. Such means may, forexample, involve open loop driving of the motor.

Other means may be employed to improve the way BEMF signals are used todetermine rotor position for the purpose of regulating commutation.

1. A control console for energizing plural power surgical handpieces,each handpiece having a power-consuming unit, said console comprising: asingle power supply; a plurality of sockets, each said socket configureto releasbly receive a separate handpiece; a controller for selectivelyproviding power to the handpieces through said sockets, said controllerconfigured to simultaneously provide power from said power supply to aplurality of handpieces.
 2. The control console of claim 1, wherein: apower supply monitor connected to said power supply for monitoring thepower consumed by said power supply and to generate a limit signal whenthe consumed power reaches a threshold value; and said controller isconfigured to receive the limit signal from said power supply and, inresponse to receiving the limit signal, terminates the application ofpower to one of the handpieces.
 3. The control console of claim 2,wherein said controller is further configured to: determine which ofsaid handpieces drawing power is drawing the most power; and when thelimit signal is received, to terminate the application of power to thehandpiece drawing the most power.